Transcript
EN 301 210 V1.1.1 (1999-03) European Standard (Telecommunications series)
Digital Video Broadcasting (DVB); Framing structure, channel coding and modulation for Digital Satellite News Gathering (DSNG) and other contribution applications by satellite
European Broadcasting Union
Union Européenne de Radio-Télévision EBU UER
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EN 301 210 V1.1.1 (1999-03)
Reference DEN/JTC-DVB-73 (b7c00ico.PDF)
Keywords broadcasting, digital, DVB, SNG, TV, video
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Copyright Notification No part may be reproduced except as authorized by written permission. The copyright and the foregoing restriction extend to reproduction in all media. © European Telecommunications Standards Institute 1999. © European Broadcasting Union 1999. All rights reserved.
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EN 301 210 V1.1.1 (1999-03)
Contents Intellectual Property Rights................................................................................................................................4 Foreword ............................................................................................................................................................4 1
Scope........................................................................................................................................................5
2
References................................................................................................................................................6
3
Symbols and abbreviations ......................................................................................................................7
3.1 3.2
4 4.1 4.2 4.3 4.4 4.4.1 4.4.2 4.4.3 4.5 4.5.1 4.5.2 4.6 4.6.1 4.6.2 4.6.3 4.7 4.7.1 4.7.1.1 4.7.1.2 4.7.1.3 4.7.2
5
Symbols ............................................................................................................................................................. 7 Abbreviations..................................................................................................................................................... 7
Transmission system ................................................................................................................................8 System definition ............................................................................................................................................... 8 Adaptation to satellite transponder characteristics............................................................................................. 9 Interfacing.......................................................................................................................................................... 9 Channel coding for QPSK modes ...................................................................................................................... 9 Transport multiplex adaptation and randomization for energy dispersal.................................................... 10 Outer coding (RS), interleaving and framing ............................................................................................. 10 Inner coding (convolutional) ...................................................................................................................... 10 Bit mapping, baseband shaping and modulation for QPSK modes.................................................................. 11 Bit mapping to QPSK constellation ........................................................................................................... 11 Baseband shaping and quadrature modulation ........................................................................................... 12 Channel coding for the optional 8PSK and 16QAM modes ............................................................................ 12 Transport multiplex adaptation and randomization for energy dispersal (8PSK and 16QAM modes) ...... 12 Outer coding (RS), interleaving and framing (8PSK and 16QAM modes) ................................................ 12 Inner coding ("pragmatic" trellis coding type) (8PSK and 16QAM modes) .............................................. 12 Bit mapping, baseband shaping and modulation for the optional 8PSK and 16QAM modes .......................... 15 Bit mapping to constellations (8PSK and 16QAM modes)........................................................................ 15 Inner coding and constellation for 8PSK 2/3 (2CBPS) ........................................................................ 16 Inner coding and constellation for 8PSK 5/6 and 8/9 (1CBPS)............................................................ 17 Inner coding and constellation for 16QAM 3/4 and 7/8 (2CBPS)........................................................ 18 Baseband shaping and modulation (8PSK and 16QAM modes) ................................................................ 20
Error performance requirements ............................................................................................................21
Annex A (normative):
Signal spectrum at the modulator output ...................................................22
Annex B (normative):
Transmission setups for interoperability tests and emergency situations.........................................................................................................24
Annex C (normative):
Implementation of the "optional" modes....................................................25
Annex D (normative):
SI implementation for DSNG and other contribution applications .........26
Annex E (informative):
Examples of possible use of the System .......................................................28
Bibliography.....................................................................................................................................................31 History ..............................................................................................................................................................32
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EN 301 210 V1.1.1 (1999-03)
Intellectual Property Rights IPRs essential or potentially essential to the present document may have been declared to ETSI. The information pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found in SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect of ETSI standards", which is available free of charge from the ETSI Secretariat. Latest updates are available on the ETSI Web server (http://www.etsi.org/ipr). Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not referenced in SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may become, essential to the present document.
Foreword This European Standard (Telecommunications series) has been produced by the Joint Technical Committee Broadcast of the European Broadcasting Union (EBU), Comité Européen de Normalisation ELECtrotechnique (CENELEC) and the European Telecommunications Standards Institute (ETSI). The work was based on the studies carried out by the European DVB Project under the auspices of the Ad Hoc Group on DSNG of the DVB Technical Module. This joint group of industry, operators and broadcasters provided the necessary information on all relevant technical matters (see bibliography). NOTE:
The EBU/ETSI JTC Broadcast was established in 1990 to co-ordinate the drafting of standards in the specific field of broadcasting and related fields. Since 1995 the JTC Broadcast became a tripartite body by including in the Memorandum of Understanding also CENELEC, which is responsible for the standardization of radio and television receivers. The EBU is a professional association of broadcasting organizations whose work includes the co-ordination of its members' activities in the technical, legal, programme-making and programme-exchange domains. The EBU has active members in about 60 countries in the European broadcasting area; its headquarters is in Geneva. European Broadcasting Union CH-1218 GRAND SACONNEX (Geneva) Switzerland Tel: +41 22 717 21 11 Fax: +41 22 717 24 81
Digital Video Broadcasting (DVB) Project Founded in September 1993, the DVB Project is a marked-led consortium of public and private sector organizations in the television industry. Its aim is to establish the framework for the introduction of MPEG-2 based digital television services. Now comprising over 200 organizations from more than 25 countries around the world, DVB fosters marked-led systems, which meet the real needs, and economic circumstances, of the consumer electronics and the broadcast industry.
National transposition dates Date of adoption of this EN:
5 February 1999
Date of latest announcement of this EN (doa):
31 May 1999
Date of latest publication of new National Standard or endorsement of this EN (dop/e):
30 November 1999
Date of withdrawal of any conflicting National Standard (dow):
30 November 1999
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EN 301 210 V1.1.1 (1999-03)
Scope
The present document describes the modulation and channel coding system (denoted the "System" for the purposes of the present document) for Digital Satellite News Gathering (DSNG) and other contribution applications by satellite. According to ITU-R Recommendation SNG.770-1 [12], SNG is defined as "Temporary and occasional transmission with short notice of television or sound for broadcasting purposes, using highly portable or transportable uplink earth stations...". The equipment should be capable of uplinking the video programme (or programmes) with its associated sound or sound programme signals. Optionally it should be capable of providing two-way co-ordination (communication) circuits and data transmission according to EN 301 222 [6]. The equipment should be capable of being set up and operated by a crew of no more than two people within a reasonably short time. Limited receiving capability should be available in the uplink terminal to assist in pointing the antenna and to monitor the transmitted signal, where possible. Digital television contribution applications by satellite consist of point-to-point or point-to-multipoint transmissions, connecting fixed or transportable uplink and receiving stations, not intended to be received by the general public. Although these applications often transmit a single TV service, the Transport Stream multiplex flexibility also allows multi-programme TV services with associated sound, including commentary sound channels and data services; in this case multiple service components are Time Division Multiplexed (TDM) on a single digital carrier. Maximum commonality with EN 300 421 [3] is maintained, such as Transport Stream multiplexing [1], scrambling for energy dispersal, concatenated error protection strategy based on Reed-Solomon coding, convolutional interleaving and inner convolutional coding. The baseline System compatibly includes (as a subset) all the transmission formats specified by EN 300 421 [3], based on Quaternary Phase Shift Keying (QPSK) modulation and is suitable for DSNG services as well as for other contribution applications by satellite. Nevertheless, other optional (annex C explains the meaning of "optional" within the present document) transmission modes are added, using Eight Phase Shift Keying (8PSK) modulation and Sixteen Quadrature Amplitude Modulation (16QAM), in order to fulfil specific application requirements. These optional modes can be very efficient in certain contribution applications by satellite. The following warnings should be taken into account while using the high spectrum efficiency modes, 8PSK and 16QAM: • they require higher transmitted EIRPs and/or receiving antenna diameters, because of their intrinsic sensitivity to noise and interferences; • they are more sensitive to linear and non-linear distortions; in particular 16QAM cannot be used on transponders driven near saturation; • they are more sensitive to phase noise, especially at low symbol rates; therefore high quality frequency converters should be used (see annex E); • the System modulation/coding schemes are not rotationally-invariant, so that "cycle-slips" and "phase snaps" in the chain can produce service interruptions; therefore frequency conversions and demodulation carrier recovery systems should be designed to avoid cycle-slips and phase snaps. The System is suitable for use on different satellite transponder bandwidths, either in single carrier per transponder or in multiple carriers per transponder (Frequency Division Multiplex, FDM) configuration. Annex E gives examples of possible use of the System. The present document: -
gives a general description of the System;
-
specifies the digitally modulated signal in order to allow compatibility between pieces of equipment developed by different manufacturers. This is achieved by describing in detail the signal processing principles at the modulator side, while the processing at the receive side is left open to different implementation solutions. However, it is necessary in the present document to refer to certain aspects of reception;
-
identifies the global performance requirements and features of the System, in order to meet the service quality targets.
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EN 301 210 V1.1.1 (1999-03)
References
The following documents contain provisions which, through reference in this text, constitute provisions of the present document. • References are either specific (identified by date of publication, edition number, version number, etc.) or non-specific. • For a specific reference, subsequent revisions do not apply. • For a non-specific reference, subsequent revisions do apply. • A non-specific reference to an ETS shall also be taken to refer to later versions published as an EN with the same number. [1]
ISO/IEC 13818-1: "Information technology; Generic coding of moving pictures and associated audio information: Systems".
[2]
ISO/IEC 13818-2: "Information technology; Generic coding of moving pictures and associated audio information: Video".
[3]
EN 300 421: "Digital Video Broadcasting (DVB); Framing structure, channel coding and modulation for 11/12 GHz satellite services".
[4]
EN 50083-9: "Cabled distribution systems for television, sound and interactive multimedia signals; Part 9: Interfaces for CATV/SMATV headends and similar professional equipment for DVB/MPEG-2 transport streams".
[5]
ETR 154: "Digital Video Broadcasting (DVB); Implementation guidelines for the use of MPEG-2 Systems, Video and Audio in satellite, cable and terrestrial broadcasting applications".
[6]
EN 301 222: "Digital Video Broadcasting (DVB); Co-ordination channels associated with Digital Satellite News Gathering (DSNG)".
[7]
Void.
[8]
EN 300 468: "Digital Video Broadcasting (DVB); Specification for Service Information (SI) in DVB systems".
[9]
ETS 300 327: "Satellite Earth Stations and Systems (SES); Satellite News Gathering (SNG) Transportable Earth Stations (TES) (13-14/11-12 GHz)".
[10]
ETS 300 673 (1997): "Radio Equipment and Systems (RES); ElectroMagnetic Compatibility (EMC) standard for 4/6 GHz and 11/12/14 GHz Very Small Aperture Terminal (VSAT) equipment and 11/12/13/14 GHz Satellite News Gathering (SNG) Transportable Earth Station (TES) equipment".
[11]
TBR 30: "Satellite Earth Stations and Systems (SES); Satellite News Gathering (SNG) Transportable Earth Stations (TES) operating in the 11-12/13-14 GHz frequency bands".
[12]
ITU-R Recommendation SNG.770-1: "Uniform operational procedures for Satellite News Gathering (SNG)".
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Symbols and abbreviations
3.1
Symbols
EN 301 210 V1.1.1 (1999-03)
For the purposes of the present document, the following symbols apply: α C/N dfree Eb/N0 fN G1,G2 I I, Q j K m M N Rs Ru T Ts X,Y
3.2
Roll-off factor Carrier-to-noise ratio Convolutional code free distance Ratio between the energy per useful bit and twice the noise power spectral density Nyquist frequency Convolutional code generators Interleaving depth [bytes] In-phase, Quadrature phase components of the modulated signal Branch index of the interleaver Convolutional code constraint length number of transmitted bits per constellation symbol Convolutional interleaver branch depth for j = 1, M = N/I Error protected frame length (bytes) Symbol rate corresponding to the bilateral Nyquist bandwidth of the modulated signal Useful bit rate after MPEG-2 [1] transport multiplexer, referred to the 188 byte format Number of bytes which can be corrected in RS error protected packet Symbol period Di-bit stream after rate 1/2 convolutional coding
Abbreviations
For the purposes of the present document, the following abbreviations apply: 16QAM 1CBPS 2CBPS 8PSK AWGN BER BS BW CBPS DSNG FDM FEC HEX IF IRD MCPC MPEG MUX OBO OCT P PDH PSK QEF QPSK RF RS SCPC SI
Sixteen Quadrature Amplitude Modulation 1 Coded Bit Per Symbol 2 Coded Bits Per Symbol Eight Phase Shift Keying Additive White Gaussian Noise Bit Error Ratio Bandwidth of the frequency Slot allocated to a service Bandwidth (at -3 dB) of the transponder Coded Bits Per Symbol Digital Satellite News Gathering Frequency Division Multiplex Forward Error Correction Hexadecimal notation Intermediate Frequency Integrated Receiver Decoder Multiple Channels Per Carrier transmission Moving Pictures Experts Group Multiplex Output Back Off Octal notation Puncturing Plesiochronous Digital Hierarchy Phase Shift Keying Quasi-Error-Free Quaternary PSK Radio Frequency Reed-Solomon Single Channel Per Carrier transmission Service Information
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SMATV SNG TCM TDM TSDT TV
EN 301 210 V1.1.1 (1999-03)
Satellite Master Antenna Television Satellite News Gathering Trellis Coded Modulation Time Division Multiplex Transport Stream Descriptor Table Television
4
Transmission system
4.1
System definition
The System is defined as the functional block of equipment performing the adaptation of the baseband TV signals, from the output of the MPEG-2 transport multiplexer (see ISO/IEC 13818-1 [1]), to the satellite channel characteristics. The System is designed to support source coding as defined in [1], [2], [5]. The System transmission frame is synchronous with the MPEG-2 multiplex transport packets (see [1]). The System shall use QPSK modulation, and optionally (annex C explains the meaning of "optional") 8PSK and 16QAM modulations, and the concatenation of convolutional and RS codes. For 8PSK and 16QAM, "pragmatic" trellis coding shall be applied, optimizing the error protection of the convolutional code defined in EN 300 421 [3]. The convolutional code is able to be configured flexibly, allowing the optimization of the system performance for a given satellite transponder bandwidth (see annex E). Digital television transmissions via satellite can be affected by power limitations, therefore ruggedness against noise and interference has been one of the design objectives of the System. On the other hand, when larger power margins are available, spectrum efficiency can be increased to reduce the cost of the space segment. Therefore the System offers many transmission modes (inner coding and modulations), giving different trade-offs between power and spectrum efficiency. For some specific contribution applications, some modes (QPSK and 8PSK) thanks to their quasi-constant envelope, are appropriate for operation with saturated satellite power amplifiers, in single carrier per transponder configuration. All the modes (including 16QAM) are appropriate for operation in quasi-linear satellite channels, in multi-carrier Frequency Division Multiplex (FDM) type applications. The following processes shall be applied to the data stream (see figure 1): • transport multiplex adaptation and randomization for energy dispersal (according to EN 300 421 [3]); • outer coding (i.e. Reed-Solomon) (according to EN 300 421 [3]); • convolutional interleaving (according to EN 300 421 [3]); • inner coding: -
punctured convolutional coding (according to EN 300 421 [3]);
-
"pragmatic" trellis coding associated with 8PSK and 16QAM (optional);
• bit mapping into constellations: -
QPSK (according to EN 300 421 [3]);
-
8PSK (optional);
-
16QAM (optional);
• squared-root raised-cosine baseband shaping: -
roll-off factor α = 0,35 according to EN 300 421 [3] for QPSK, 8PSK and 16QAM;
-
additional optional roll-off factor α = 0,25 (for the optional modulations 8PSK and 16QAM);
• quadrature modulation (according to EN 300 421 [3]).
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Coders
EN 301 210 V1.1.1 (1999-03)
Convolutional
P r o g r a m m e Transport RS (204,188)
type
Video Audio
MUX
2
Data
MUX Adaptation & Energy Dispersal
1 MUX
QPSK 8PSK (optional) 16QAM (optional)
a = 0 ,3 5 (se e n o te )
Bit
Outer Coder
Interleaver (I=12)
Inner Coder
Mapping Into Constellation
Baseband Shaping
to the RF Satellite Channel
Quadrature Modulator
n According to EN 300 421 MPEG-2 Source Coding and Multiplexing
NOTE:
According to EN 300 421 for QPSK Satellite Channel Adapter
α = 0,25 for 8PSK and 16QAM (additional and optional).
Figure 1: Functional block diagram of the System If the received signal is above C/N and C/I threshold, the Forward Error Correction (FEC) technique adopted in the System is designed to provide a "Quasi Error Free" (QEF) quality target. The QEF means less than one uncorrected error-event per transmission hour, corresponding to Bit Error Ratio (BER) = 10-10 to 10-11 at the input of the MPEG-2 demultiplexer.
4.2
Adaptation to satellite transponder characteristics
The symbol rate shall be matched to given transponder characteristics, and, in the case of multiple carriers per transponder (FDM), to the adopted frequency plan. Examples of possible use of the System are given in annex E.
4.3
Interfacing
The System, as defined in the present document, shall be delimited by the following interfaces given in table 1. Table 1: System interfaces Location Transmit station
Interface Interface type Connection Input MPEG-2 [1], [2], [4] transport multiplex (note 1) from MPEG-2 multiplexer Output 70/140 MHz IF, L-band IF, RF to RF devices Receive installation Output MPEG-2 transport multiplex [1], [2], [4] (note 1) to MPEG-2 demultiplexer Input 70/140 MHz IF, L-band IF from RF devices NOTE 1: For interoperability reasons, the Asynchronous Serial Interface (ASI) with 188 bytes format, data burst mode (bytes regularly spread over time) is recommended. NOTE 2: The 70 MHz IF may imply limitation on the maximum symbol rate.
4.4
Channel coding for QPSK modes
The information on QPSK modulation summarized here is only partial. Refer to EN 300 421 [3] for the complete specification.
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4.4.1
EN 301 210 V1.1.1 (1999-03)
Transport multiplex adaptation and randomization for energy dispersal
This processing shall be in accordance with EN 300 421 [3], as summarized in the following. The System input stream shall be organized in fixed length packets, following the MPEG-2 transport multiplexer (see ISO/IEC 13818-1 [1]). The total packet length of the MPEG-2 transport Multiplex (MUX) packet is 188 bytes. This includes 1 sync-word byte (i.e. 47HEX). In order to comply with ITU Radio Regulations and to ensure adequate binary transitions, the data of the input MPEG-2 multiplex shall be randomized. To provide an initialization signal for the descrambler, the MPEG-2 sync byte of the first transport packet in a group of eight packets is bit-wise inverted from 47HEX to B8HEX. This process is referred to as the "Transport Multiplex Adaptation".
4.4.2
Outer coding (RS), interleaving and framing
This processing shall be in accordance with EN 300 421 [3], as summarized in the following. Reed-Solomon RS (204,188, T = 8) shortened code, from the original RS(255,239, T = 8) code, shall be applied to each randomized transport packet (188 bytes) to generate an error protected packet. Reed-Solomon coding shall also be applied to the packet sync byte, either non-inverted (i.e. 47HEX) or inverted (i.e. B8HEX). Convolutional interleaving with depth I = 12 shall be applied to the error protected packets. This results in an interleaved frame, composed of overlapping error protected packets and delimited by inverted or non-inverted MPEG-2 [1] sync bytes (preserving the periodicity of 204 bytes).
4.4.3
Inner coding (convolutional)
Processing of the convolutional encoder shall be in accordance with EN 300 421 [3], as summarized in the following. The System shall allow for a range of punctured convolutional codes, based on a rate 1/2 mother convolutional code with constraint length K = 7 corresponding to 64 trellis states (figure 2). This will allow selection of the most appropriate level of error correction for a given service or data rate. The System shall allow convolutional coding with code rates of 1/2, 2/3, 3/4, 5/6 and 7/8. X output (171 octal) Modulo-2 adder
serial input bit-stream
1-bit
1-bit
1-bit
1-bit
1-bit
1-bit
delay
delay
delay
delay
delay
delay
Modulo-2 adder Y output (133 octal)
Figure 2: Convolutional code of rate 1/2 The punctured convolutional code shall be used as given in table 2, according to EN 300 421 [3]. NOTE:
At the receiver, each of the code rates and puncturing configurations is in a position to be tried until lock is acquired. Phase ambiguity in the demodulator is able to be resolved by decoding the MPEG-2 [1] sync byte delimiting the interleaved frame. Automatic receiver synchronization is an important feature in DSNG applications, to simplify and accelerate the satellite connection setup.
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EN 301 210 V1.1.1 (1999-03)
Table 2: Punctured code definition Original code 1/2 K
G1 (X)
G2 (Y)
P
dfree
P
171OCT 133OCT
10
Y: 1
Y:11
C1 = X1 C2 = Y1
NOTE:
dfree
P
6
5/6
dfree
P
7/8 dfree
5
Y: 1 1 0
Y: 1 1 0 1 0
P
dfree
X: 1 0 0 0 1 0 1
X: 1 0 1 0 1
X: 1 0 1
X:10
X: 1 7
Code rates 3/4
2/3
4
Y: 1 1 1 1 0 1 0
C1 = X1 Y2 Y3
C1 = X1 Y2
C1 = X1 Y2 Y4
C1 = X1 Y2 Y4 Y6
C2 = Y1 X3 Y4
C2 = Y1 X3
C2 = Y1 X3 X5
C2 = Y1 Y3 X5 X7
3
1 = transmitted bit 0 = non transmitted bit
4.5
Bit mapping, baseband shaping and modulation for QPSK modes
4.5.1
Bit mapping to QPSK constellation
For QPSK, inner coding and mapping into constellation shall be in accordance with EN 300 421 [3], as summarized in the following. The serial input stream (see figures 2 and 3) shall be directly fed into the convolutional encoder. The outputs C1 and C2 of the punctured convolutional encoder shall be directly sent to the QPSK mapper.
C1
X serial
Convolutional Encoder
Puncturing
Baseband shaping
to QPSK
bit-stream Y
I bit mapping
C2
Quadrature Modulation
constellation Q m=2 bits per symbol
rate k/n convolutional code
Figure 3: Inner coding principle for QPSK The System shall employ conventional Gray-coded QPSK modulation with absolute mapping (no differential coding). Bit mapping in the QPSK constellation shall follow figure 4. If the normalization factor 1/√2 is applied to the I and Q components, the corresponding average energy per symbol becomes equal to 1. Q
C2=0 C1=1
C2=0 C1=0
1
1 C2=1 C1=1
I C2=1 C1=0
Figure 4: Bit mapping into QPSK constellation
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4.5.2
EN 301 210 V1.1.1 (1999-03)
Baseband shaping and quadrature modulation
Prior to modulation, the I and Q signals (mathematically represented by a succession of Dirac delta functions, multiplied by the amplitudes I and Q, spaced by the symbol duration Ts = 1/Rs) shall be square root raised cosine filtered. The roll-off factor shall be α = 0,35. The baseband square root raised cosine filter shall have a theoretical function defined by the following expression:
H( f ) =1
for
f < f N (1 − α ) 1
2 1 1 π fN − f H ( f ) = + sin 2 fN α for f N (1 − α ) ≤ f ≤ f N (1 + α ) 2 2
H ( f ) = 0 for f > f N (1 + α ) , where:
fN =
1 R = s is the Nyquist frequency and α is the roll-off factor. 2Ts 2
A template for the signal spectrum at the modulator output is given in annex A.
4.6
Channel coding for the optional 8PSK and 16QAM modes
Some details on QPSK are also repeated in the following for completeness.
4.6.1
Transport multiplex adaptation and randomization for energy dispersal (8PSK and 16QAM modes)
This processing shall be in accordance with EN 300 421 [3] (see subclause 4.4.1).
4.6.2
Outer coding (RS), interleaving and framing (8PSK and 16QAM modes)
This processing shall be in accordance with EN 300 421 [3] (see subclause 4.4.2).
4.6.3
Inner coding ("pragmatic" trellis coding type) (8PSK and 16QAM modes)
The inner coding schemes produce pragmatic Trellis Coded Modulations (TCM) (see bibliography), which are an extension of the coding method adopted in EN 300 421 [3] (see subclause 4.4.3). The pragmatic trellis coded modulations shall be produced by the principle scheme shown in figure 5 and by tables 3 and 4. The byte-parallel stream (P0 to P7 in figure 5) at the output of the convolutional interleaver shall be conveyed to a parallel-to-parallel converter (note 1), which shall split the input bits into two branches, depending on the selected modulation / inner coding mode. NOTE 1: The schemes of the parallel-to-parallel converters have been selected in order to reduce, on average, the byte error-ratio at the input of the Reed-Solomon decoder (high concentration of bit-errors in bytes). Therefore the bit error ratio (BER) after RS correction is reduced. Furthermore some MPEG sync-bytes are regularly convolutionally encoded. The parallel-to-parallel converter is synchronized in such a way that the MPEG sync-bytes, in the normal form (47HEX) or bit-wise inverted form (B8HEX), regularly appear in byte A (see table 3). When an MPEG sync byte (47HEX) is transmitted, the A byte shall be coded as follows: A = (A7, …, A0) = 01000111.
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EN 301 210 V1.1.1 (1999-03)
The signal NE of the non-encoded branch shall generate, through the Symbol Sequencer, a sequence of signals U, each to be transmitted in a modulated symbol. These bits generate parallel transitions in the trellis code, and are only protected by a large Euclidean distance in the signal space (see bit mapping to constellation). The signal E in the encoded branch shall be processed by the punctured convolutional encoder according to EN 300 421 [3] (see subclause 4.4.3). These bits shall generate, through the Symbol Sequencer, a sequence of signals C, each to be transmitted in a modulated symbol. The specific coding scheme for each constellation and coding rate shall follow the specification given in subclauses 4.7.1.1 to 4.7.1.3. A pragmatic trellis code characterized by c Coded Bits Per Symbol (c = 1 or 2) will be indicated in the following with the notation cCBPS (note 2). NOTE 2: The 1CBPS schemes require lower processing speed of the TCM decoder compared to 2CBPS schemes. The selections have been carried-out on the basis of the best performance in the presence of AWGN. Symbol Sequencer over D symbols
non-encoded branch NE
I
U
P0 bit mapping
X P/P
Convolutional Encoder
P/S
P7
C
E encoded branch
P/P= parallel-to-parallel P/S= parallel-to-serial
constellation Q
Y
bytes from interleaver
to
Puncturing
1 or 2 coded bits rate k/n convolutional code
per symbol
Figure 5: Inner trellis coder principle NOTE 3: The QPSK modes described in subclause 4.5 can be generated by the TCM scheme of figure 5, without non-encoded bits. The input parallel-to-parallel conversion shall be defined by table 3. The generic input bytes P = (P7,…,P0) are taken from the sequence A (first), B, D, F, G, H, L (last) (the letters C, E, I, J, K are not used to avoid notation conflicts). For QPSK, the parallel-to-parallel converter reduces to a parallel-to-serial converter.
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EN 301 210 V1.1.1 (1999-03)
Table 3: Parallel-to-parallel conversion Input MODE QPSK 8PSK - 2/3
8PSK - 5/6
LAST A0 B0 A0 G3 G2 G1 G0 A0
A1 B1 A1 G7 G6 G5 G4 A1
A2 B2 A2 F3 F2 F1 F0 A2
A3 B3 A3 F7 F6 F5 F4 A3
D1 D0 A0 L3 L2 L1 L0 H2 H1 H0
D3 D2 A1 L7 L6 L5 L4 H5 H4 H3
D5 D4 A2 G3 G2 G1 G0 F0 H7 H6
D7 D6 A3 G7 G6 G5 G4 F3 F2 F1
A4 B4 A4 D3 D2 D1 D0 A4 F5 F4 F3 F2 F1 F0 A1 A0 B1 B0 A4 D3 D2 D1 D0 F6 F5 F4
8PSK - 8/9
16QAM - 3/4
16QAM - 7/8
P
Output A5 B5 A5 D7 D6 D5 D4 A5 F7 F6 D3 D2 D1 D0 A3 A2 B3 B2 A5 D7 D6 D5 D4 A1 A0 F7
A6 B6 A6 B3 B2 B1 B0 A6 B1 B0 D7 D6 D5 D4 A5 A4 B5 B4 A6 B3 B2 B1 B0 A4 A3 A2
FIRST A7 B7 A7 B7 B6 B5 B4 A7 B7 B6 B5 B4 B3 B2 A7 A6 B7 B6 A7 B7 B6 B5 B4 A7 A6 A5
⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒
E1 NE1 E1 NE4 NE3 NE2 NE1 E1 NE6 NE5 NE4 NE3 NE2 NE1 E2 E1 NE2 NE1 E1 NE4 NE3 NE2 NE1 E3 E2 E1
The parallel-to-serial converter in figure 5 shall output first the E bit associated with highest index. The parallel-to-serial converter and the convolutional encoder shall introduce no relative delay between the coded and non-encoded branches (i.e., the bit timing between non-encoded and encoded branches as indicated in table 4 shall be preserved). The puncturing and symbol sequencer functions shall follow the definition given in table 4.
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EN 301 210 V1.1.1 (1999-03)
Table 4: Puncturing and Symbol sequencer definition MODE
LAST SYMBOL
QPSK - 1/2 QPSK - 2/3
Y4 Y3
X5 Y4 X5 Y4
X3 Y2 X3 Y2 X3 Y2 Y3 Y2
NE2 NE1 Y2
NE2 NE1 Y1 NE4 NE3 Y1
QPSK - 3/4 QPSK - 5/6 QPSK - 7/8
X7 Y6
8PSK - 2/3
8PSK - 5/6
8PSK - 8/9
16QAM - 3/4
16QAM - 7/8
NE2 NE1 X3 Y2
FIRST SYMBOL Y1 X1 Y1 X1 Y1 X1 Y1 X1 Y1 X1 NE1 Y1 X1 NE4 NE3 X1 NE6 NE5 X1 NE2 NE1 Y1 X1 NE4 NE3 Y1 X1
Output ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒ ⇒
C2 C1 C2 C1 C2 C1 C2 C1 C2 C1 U1 C2 C1 U2 U1 C1 U2 U1 C1 U2 U1 C2 C1 U2 U1 C2 C1
4.7
Bit mapping, baseband shaping and modulation for the optional 8PSK and 16QAM modes
4.7.1
Bit mapping to constellations (8PSK and 16QAM modes)
Bit mapping into constellations is carried out by associating the m input bits (U, C in figure 5) with the corresponding vector in the Hilbert signal space belonging to the chosen constellation. The possible constellations are 8PSK (m = 3 bit) and 16QAM (m = 4 bit). Optimum mapping of coded and uncoded bits into constellation is different in the cases of 1CBPS or 2CBPS schemes. The Cartesian representation of each vector will be indicated by I, Q (i.e., the in-phase and quadrature components).
ETSI
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4.7.1.1
EN 301 210 V1.1.1 (1999-03)
Inner coding and constellation for 8PSK 2/3 (2CBPS)
For 8PSK rate 2/3, inner coding shall comply with the principle of figure 6. non-encoded branch
D=1 symbol
P0 P/P
I
U1
NE1
Rate 1/2 Convolutional Encoder
E1
P7
Y
C2
bit mapping
X
C1
constellation
to 8PSK Q
encoded branch (2 coded bits per symbol) P/P=parallel-to-parallel
Figure 6: Inner coding principle for 8PSK rate 2/3 (2CBPS) For rate 2/3, bit mapping in the 8PSK constellation shall follow figure 7. If the normalization factor 1/√2 is applied to the I and Q components, the corresponding average energy per symbol becomes equal to 1. U1=0 C2=1 C1=1 U1 =0 C2=1 C1=0
Q
U1 =0 C2=0 C1=1 U 1=0 C2=0 C1=0
1
1
U 1=1 C2=0 C1=0
I U1 =1 C2=1 C1=0
U1 =1 C2=1 C1=1
U1 =1 C2=0 C1=1
Figure 7: Bit mapping into 8PSK constellation for rate 2/3 (2CBPS)
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4.7.1.2
EN 301 210 V1.1.1 (1999-03)
Inner coding and constellation for 8PSK 5/6 and 8/9 (1CBPS)
For 8PSK rate 5/6 inner coding shall comply with the principle of figure 8. S ymbol s equencer
A first G,F,D,B,A
non-encoded branch
NE4
D=2 symbols U2
NE3
bit mapping
P0
U1 C1
NE2
P/P
NE1
P7
1st symbol
to 8PSK
I Q
constellation
X Rate 1/2 Convolutional
E1
Encoder Y
encoded branch
U2
2nd symbol
U1
bit mapping
I
C1
to 8PSK
Q
constellation
P/P=parallel-to-parallel
(1 coded bit per symbol)
Figure 8: Inner coding principle for 8PSK rate 5/6 (1CBPS) For 8PSK rate 8/9, inner coding shall comply with the principle of figure 9. Symbol sequencer A First
non-encoded branch NE6
D=3 symbols U2 1st symbol U1
F,D,B,A NE5
to 8PSK C1
NE4 NE3
P0
U2
P/P P7
U1
NE2 NE1
E2
bit mapping
P/S
Rate 1/2 Convolutional
2nd symbol bit mapping
Puncturing
constellation
3rd symbol bit mapping
I
to 8PSK
Q
C1 constellation
rate 2/3 convolutional code
P/S= parallel-to-serial P/P= parallel-to-parallel
U2 U1
X
encoded branch
I Q
Y
Encoder E1
Q
constellation
to 8PSK C1
I
(1 coded bit per symbol) E-serial
Figure 9: Inner coding principle for 8PSK rate 8/9 (1CBPS)
ETSI
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EN 301 210 V1.1.1 (1999-03)
For 8PSK rate 8/9 the timing of the P/S converter and convolutional encoder shall follow the principle scheme as follows: E-inputs
E2 E1
E-serial
E2
E1
Y X
Y1 X1 first
Y2 X2 last time
For rates 5/6 and 8/9, bit mapping in the 8PSK constellation shall comply with figure 10. If the normalization factor 1/√2 is applied to the I and Q components, the corresponding average energy per symbol becomes equal to 1.
U2 =0 U1=1 C1=0 U2 =0 U1=1 C1=1
Q
U2 =0 U1=0 C1=1 U2 =0 U1=0 C1=0
1
1
U2 =1 U1=0 C1=0
I U2 =1 U1=1 C1=1
U2 =1 U1=1 C1=0
U2 =1 U1=0 C1=1
Figure 10: Bit mapping into 8PSK constellation for rates 5/6 and 8/9 (1CBPS)
4.7.1.3
Inner coding and constellation for 16QAM 3/4 and 7/8 (2CBPS)
16QAM modes are suitable for quasi-linear transponders. For 16QAM rate 3/4 inner coding shall comply with the principle of figure 11. D=1 symbol A First
Symbol sequencer
non-encoded branch D,B,A NE2
P0 P/P
U2 C2
Q
NE1
bit mapping
Y
P7
to 16QAM
Rate 1/2 Convolutional E1 encoded branch
Q
U1
constellation
C1
I
Encoder X
I
P/P=parallel-to-parallel (2 coded bits per symbol)
Figure 11: Inner coding principle for 16QAM rate 3/4 (2CBPS)
ETSI
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EN 301 210 V1.1.1 (1999-03)
For 16QAM rate 7/8, inner coding shall comply with the principle of figure 12. A first
Symbol
D=2 symbols
sequencer
L,H,G,F,D,B,A
non-encoded branch NE4
U2
NE3
C2
1st symbol bit mapping
P0
U1
NE2 P/P
P7
to 16QAM
C1
constellation
U2
2nd symbol
I Q
NE1 Y E3
P/S
E2
Rate 1/2 Convolutional
Puncturing
Encoder
C2 X
E1
U1 P/S= parallel-to-serial P/P= parallel-to-parallel
E-serial
rate 3/4 convolutional code
bit mapping
I
to 16QAM
Q
constellation
C1
encoded branch (2 coded bits per symbol)
Figure 12: Inner coding principle for 16QAM rate 7/8 (2CBPS) For 16QAM rate 7/8 the timing of the P/S converter and convolutional encoder shall comply with the principle scheme as follows: E3 E2 E1
E-inputs
E-serial
E3
E2
E1
Y X
Y1 X1 first
Y2 X2
Y3 X3 last
For rates 3/4 and 7/8, bit mapping in the 16QAM constellation shall comply with figure 13. If the normalization factor 1/√10 is applied to the I and Q components, the corresponding average energy per symbol becomes equal to 1.
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EN 301 210 V1.1.1 (1999-03)
Q 3
1
1
I
3
0 -3 U1=1 C1 =1
-1 U1=1 C1=0
0 1 U1=0 C1 =1
3 U1=0 C1 =0
-3 U2=1 C2=1
I
-1 U2=1 C2 =0
1 U2=0 C2 =1
3 U2 =0 C2 =0
Q
Figure 13: Bit mapping into I and Q axes for 16QAM constellation, rates 3/4 and 7/8 (2CBPS)
4.7.2
Baseband shaping and modulation (8PSK and 16QAM modes)
Prior to modulation, the I and Q signals (mathematically represented by a succession of Dirac delta functions, multiplied by the amplitudes I and Q, spaced by the symbol duration Ts = 1/Rs) shall be square root raised cosine filtered (see subclause 4.5.2). The roll-off factor shall be α = 0,35 for 8PSK and 16QAM. In addition to α = 0,35, for 8PSK and 16QAM the narrow roll-off factor α = 0,25 can optionally be used (see annex E). A template for the signal spectrum at the modulator output is given in annex A.
ETSI
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5
EN 301 210 V1.1.1 (1999-03)
Error performance requirements
The modem, connected in the IF loop, shall meet the BER versus Eb/No performance requirements given in table 5. Table 5: IF-Loop performance of the System Modulation
Inner code rate
Spectral efficiency (bit/symbol)
Modem implementation margin (dB)
Required Eb/No (note 1) for BER = 2 x 10-4 before RS QEF after RS (dB) 1/2 0,92 0,8 4,5 2/3 1,23 0,8 5,0 QPSK 3/4 1,38 0,8 5,5 5/6 1,53 0,8 6,0 7/8 1,61 0,8 6,4 8PSK 2/3 1,84 1,0 6,9 (optional) 5/6 2,30 1,4 8,9 8/9 (note 3) 2,46 1,5 9,4 16QAM 3/4 (note 3) 2,76 1,5 9,0 (optional) 7/8 3,22 2,1 10,7 NOTE 1: The figures of Eb/No are referred to the useful bit-rate Ru (188 byte format, before RS coding) (so takes account of the factor 10 log 188/204 ≅ 0,36 dB due to the Reed-Solomon outer code) and include the modem implementation margins. For QPSK the figures are derived from EN 300 421 [3]. For 8PSK and 16QAM, modem implementation margins which increase with the spectrum efficiency are adopted, to cope with the larger sensitivity associated with these schemes. NOTE 2: Quasi-Error-Free (QEF) means approximately less than one uncorrected error event per hour at the input of the MPEG-2 demultiplexer. Other residual error rate targets could be defined for "contribution quality" transmissions. The bit error ratio (BER) of 2 x 10-4 before RS decoding corresponds approximately to a byte error ratio between 7 x 10-4 and 2 x 10-3 depending on the coding scheme. NOTE 3: 8PSK 8/9 is suitable for satellite transponders driven near saturation, while 16QAM 3/4 offers better spectrum efficiency for quasi-linear transponders, in FDMA configuration.
Examples of possible use of the System are given in annex E.
ETSI
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EN 301 210 V1.1.1 (1999-03)
Annex A (normative): Signal spectrum at the modulator output For QPSK modulation, the signal spectrum at the modulator output shall be in accordance with EN 300 421 [3], relevant to a roll-off factor α = 0,35. For the optional modulations 8PSK and 16QAM, the signal spectrum at the modulator output shall be in accordance with EN 300 421 [3], relevant to a roll-off factor α = 0,35. As an option, the signal spectrum can correspond to a narrower roll-off factor α = 0,25. Figure A.1 gives a template for the signal spectrum at the modulator output for a roll-off factor α = 0,35. Figure A.1 also represents a possible mask for a hardware implementation of the Nyquist modulator filter as specified in subclauses 4.5.2 and 4.7.2. The points A to S shown on figures A.1 and A.2 are defined in table A.1 for roll-off factors α = 0,35 and α = 0,25. The mask for the filter frequency response is based on the assumption of ideal Dirac delta input signals, spaced by the symbol period Ts = 1/Rs = 1/2fN, while in the case of rectangular input signals a suitable x/sin x correction shall be applied on the filter response. Figure A.2 gives a mask for the group delay for the hardware implementation of the Nyquist modulator filter.
Relative power (dB) 10
A
C
E
G
I J
0 B
D
F
H
L K
-10 P
M -20
Q
-30 N
-40 S -50 0
0,5
1
1,5
2
2,5
f/f N Figure A.1: Template for the signal spectrum mask at the modulator output represented in the baseband frequency domain (roll-off factor α = 0,35)
ETSI
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23
EN 301 210 V1.1.1 (1999-03)
Group delay x f N 0,2 L 0,15 0,1 J 0,05
A
C
G
E
I
0 -0,05
0,00 B D
0,50 F
1,00
1,50
2,00
2,50
3,00
H K
-0,1 -0,15 M -0,2
f / fN
Figure A.2: Template of the modulator filter group delay (roll-off factors α = 0,35 and α = 0,25) Table A.1: Definition of points given in figures A.1 and A.2 Point A B C D E F G H I J K L M N P Q S NOTE:
Frequency for α = 0,35 0,0 fN 0,0 fN 0,2 fN 0,2 fN 0,4 fN 0,4 fN 0,8 fN 0,8 fN 0,9 fN 1,0 fN 1,0 fN 1,2 fN 1,2 fN 1,8 fN 1,4 fN 1,6 fN 2,12 fN
Frequency for α = 0,25 (note) 0,0 fN 0,0 fN 0,2 fN 0,2 fN 0,4 fN 0,4 fN 0,86fN 0,86 fN 0,93 fN 1,0 fN 1,0 fN 1,13 fN 1,13 fN 1,60 fN 1,30 fN 1,45 fN 1,83 fN
Relative power (dB) +0,25 -0,25 +0,25 -0,40 +0,25 -0,40 +0,15 -1,10 -0,50 -2,00 -4,00 -8,00 -11,00 -35,00 -16,00 -24,00 -40,00
Group delay
The roll-off factor α = 0,25 is optional and applicable to 8PSK and 16QAM only.
ETSI
+0,07 / fN -0,07 / fN +0,07 / fN -0,07 / fN +0,07 / fN -0,07 / fN +0,07 / fN -0,07 / fN +0,07 / fN +0,07 / fN -0,07 / fN -
24
EN 301 210 V1.1.1 (1999-03)
Annex B (normative): Transmission setups for interoperability tests and emergency situations At least one user definable setup shall be provided by the DSNG equipment to be able to cope with interoperability tests and emergency situations. This setup shall be easily selectable in the equipment. Table B.1 shows possible examples of Transmission Setups which can be used for interoperability tests and emergency situations. Other examples may be derived from table E.1 of annex E. Table B.1: Possible examples of Transmission Setups MPEG 2 Coding profile MP@ML MP@ML MP@ML MP@ML MP@ML 422P@ML
NOTE:
Bit Rate Ru (after MUX) (Mbit/s) 3,0719 4,6078 6,3120 8,2941 8,4480 21,5030
Modulation QPSK QPSK QPSK QPSK QPSK QPSK
Code rate 3/4 3/4 3/4 3/4 3/4 7/8
Symbol Rate Rs (Mbaud) 2,222 3,333 4,566 6,000 6,1113 13,3332
Total bandwidth 1,35 Rs (MHz) 3,000 4,500 6,160 8,100 8,250 18,000
For bit-rates and symbol rates, typical accuracy is ± 10 ppm.
Tables B.2 and B.3 show example Coding Setups for Ru = 8,448 Mbit/s and for Ru = 21,5030 Mbit/s which can be used for interoperability tests and emergency situations. Table B.2: Example Coding Setups for MP@ML at 8,448 Mbit/s Components
Video Audio Data VBI data
No. of channels
1 1 Stereo pair Not used Not used
Bit rate
Coding
(Elementary Stream) 7,60 Mbit/s 256 kbit/s
No Low delay MPEG1 Layer 2
Video Resolution and Audio Sampling Rate Video frame rate Video frame rate 25 Hz 29,97 Hz 720 x 576 720 x 480 48 kHz 48 kHz
Table B.3: Example Coding Setups for 422@ML at 21,503 Mbit/s Components
Video Audio Data VBI data
No. of channels
1 1 Stereo pair Not used Not used
Bit rate
Coding
(Elementary Stream) 20,00 Mbit/s 384 kbit/s
No Low delay MPEG1 Layer 2
Video Resolution and Audio Sampling Rate Video frame rate Video frame rate 25 Hz 29,97 Hz 720 x 576 720 x 480 48 kHz 48 kHz
NOTE 1: It would be desirable that the Transport Stream at the input of the Modulator is not scrambled (no conditional access). NOTE 2: I, B or P picture type are allowed in the coded video stream.
ETSI
25
EN 301 210 V1.1.1 (1999-03)
Annex C (normative): Implementation of the "optional" modes Within the present document, a number of modes and mechanisms have been defined as "Optional". For example, trellis coded 8PSK and 16QAM modes are optional. Modes and mechanisms explicitly indicated as "optional" within the present document need not be implemented in the equipment to comply with the present document. Nevertheless, when an "optional" mode or mechanism is implemented, it shall comply with the specification as given in the present document.
ETSI
26
EN 301 210 V1.1.1 (1999-03)
Annex D (normative): SI implementation for DSNG and other contribution applications In DSNG transmissions, editing of the SI tables in the field may be impossible due to operational problems. Therefore, only the following MPEG2-defined SI tables PAT, PMT and Transport Stream Descriptor Table (TSDT) are mandatory. The first descriptor in the TSDT descriptor loop shall contain the descriptor which identifies the Transport Stream as of type "CONA" (with reference to the "CONtribution" Application). Syntax
no. of bitsidentifier
transport-stream-descriptor (){ descriptor_tag
8
uimsbf
descriptor_length
8
uimsbf
for (i=0;i
